1. Field of the Invention
This disclosure relates to a roller member used for an image forming apparatus, a roller supporting mechanism provided with the roller member, and the image forming apparatus.
An image forming apparatus is an apparatus that forms images on recording media. Examples of an electrophotographic image forming apparatus include, for example, electrophotographic copying machines, electrophotographic printers (LED printers, laser beam printers), facsimile apparatuses, and word processors.
2. Description of the Related Art
In the related art, an electrophotographic image forming apparatus (hereinafter, referred to as an image forming apparatus) is provided with a process device having a photo sensitive drum (electrophotographic photosensitive drum) and acting on the photosensitive drum. Examples of the process device include a voltage application apparatus configured to apply electric charge on the photosensitive drum, a developing device configured to supply developer (hereinafter, referred to as “toner”) to the photosensitive drum, and a cleaning device configured to clean toner failed to be transferred and remaining on a surface of the photosensitive drum.
Examples of a charging device in the voltage application apparatus include a roller charging system using a roller member. In the roller charging system, charging of the surface of the photosensitive drum is achieved by bringing a charging roller, which is a conductive resilient roller, into bias abutment with the photosensitive drum and applying a voltage thereto. The charging roller generally has a form having a resilient layer covering a metallic shaft over the entire area in a longitudinal direction other than both ends (Japanese Patent Laid-Open No. 2013-109209).
Examples of the metallic shaft of the charging roller include a form using a cylindrical-shaped metallic shaft (Japanese Patent Laid-Open No. 2010-230748).
However, in the cylindrical-shaped metallic shaft formed by a press work may have a projecting portion present on an end surface of the metallic shaft by a requirement in a manufacturing process. In this case, if the metallic shaft is rotatably supported by a bearing portion, the projecting portion may be caught by the bearing portion and hence abrasion of the bearing portion may be accelerated. Alternatively, smooth rotation of the roller member may be impaired by the projecting portion.
Therefore, resisting abrasion of the bearing by rotation of the roller member or rotating the roller member smoothly is currently required.